This invention relates to refractory castable compositions based on fused oxides including a vitreous phase. These compositions have low porosity, high strength and high hot abrasion resistance.
Refractory materials are used in virtually all petroleum refining and process industry units that operate at elevated temperatures. The temperatures inside fluid catalytic cracking units, for example, can reach as high as 800.degree. C. Thus, these and other units must be lined with a material that can provide high resistance to such elevated high temperatures and which is inert to the chemicals and atmospheres encountered during processing.
For some time, units were lined with fire brick, but it was found that such linings possessed poor abrasion resistance. It is now standard in the industry to line such units with a refractory castable composition with good insulation value and abrasion resistance. The units are lined by building metal forms on the inside of the unit, directing the refractory castable composition into the forms while vibrating at high intensity, allowing the composition to set and then removing the metal forms.
Although refractory castable compositions useful for lining units as described above are currently available on the market, there is a need for higher performance, longer lasting refractories. The refractory linings in catalytic cracking units are generally two to four inches thick, and up to 400 tons of refractory castable composition can be required to line a single unit. Needless to say, the cost of repairing or replacing such a refractory lining can be quite high. Even more important than the replacement cost of the lining is the cost of the downtime of the unit during the repair which can take several weeks.